A can of White Airtight paint
passivhaus airtight air barrier
Passivhaus-certified Airtight White applied in heritage building basement.
Passivhaus-certified Airtight White applied in heritage building basement.
Airtight White liquid airtight vapour control membrane – Passivhaus certified
A+ Certified Passive House Certified BBA Certified
SKU: IM/00AW10

Airtight White – Vapour Control Paint (11.4kg) – Spray / Roller Applied

$258.97

Product Collection: Passive Purple
Applied By: Spray or Roller
Colour: White
Size: 11.4kg
Certification: BS Fire Class C | EN 13501-1:2018, cl. 11
Sample Available Here

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Passive Purple airtight white vapour control membrane paint is the world’s most airtight liquid vapour control membrane that comes in white. BBA certified and Passivhaus certified airtight vapour control membrane.

Simply apply Supergrip to Airtight White to allow plaster and dot and dab adhesive to adhere to Airtight White

Coverage
OSB: 13 – 14 Sqm

KEY POINTS:

  • Passivhaus certified
  • BBA certified
  • M1 class, voc free (volatile organic compound)
  • Fire class c
  • Up to 300m2 a day per operative
  • 0.03ach (air changes per hour)
  • Adheres to any substrate
  • Radon & Methane barrier
  • Consumption will depend on the substrate the product is being applied to

Choose Colour:

Please contact us for information on other colour variants.

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    Passivhaus Airtight Sealant - 600ml

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  • Key Details

    Why Choose Passive Purple Airtight White?

    Passive Purple Airtight White is a high-performance liquid airtight vapour control membrane, engineered for projects where airtightness, safety, and sustainability matter most. Certified, tested, and trusted across the industry, it delivers the ultimate balance of speed, protection, and reliability.

    • 🔒 Certified Performance – Fully BBA Certified and Passivhaus Certified, Airtight White meets the toughest standards for airtightness and building integrity.

    • ☢️ Radon Barrier Protection – Airtight White doubles as a radon barrier, safeguarding your building from harmful ground gases and ensuring a healthier indoor environment.

    • ⚡ Fast Application, Lower Labour Costs – With airless spray application, a single installer can cover up to 300m² per day, dramatically speeding up build times and reducing costs.

    • 🌍 Safe & Sustainable – Rated M1 Class and completely VOC-free, Airtight White is water-based, free from harmful chemicals, and safe for both users and the environment.

    • 🔥 Fire Safety Advantage – Unlike paper membranes (Class E), Airtight White achieves a Fire Class C rating, giving your project a higher level of built-in fire protection.

    • 🏆 Proven Airtightness – With airtightness results of 0.6 ACH and below, Airtight White helps you achieve Passivhaus standards with confidence – whether you’re aiming for certification or simply building to a higher energy efficiency level.

    👉 Passive Purple Airtight White is the smart choice for builders, architects, and retrofit specialists who need a certified, safe, and high-performance airtight membrane that goes beyond traditional tapes and foils.

  • Description

    Now we know what you’re thinking. Is it a nasty chemical? Well, No! Passive Purple Airtight White – airtight membrane is a VOC-free, water-based vapour control membrane. It’s completely free of any nasty chemicals or fumes… What’s more, as a water-based product, cleaning your paintbrushes and airless spray device is a smooth, no mess task.

    Passive Purple Airtight White adheres to any form of construction, allowing you to achieve maximum results for your desired goal. Once dry, Airtight White forms an extremely tough yet flexible polymer, water control membrane allowing it to move with the building settlement while also being super effective against impact damage. Airtight White, airtight membrane eliminates the inevitable rips, tears, unstuck tapes, staple holes, and many repairs you would expect to find on the classic paper membranes.

    We have eradicated the need for paper, tapes and staples through this product, which eliminates all the problems that came with it (labour time, large quantity of damage repairs and waste material).

    Passive Purple Airtight White saves you money and delivers well above your goals.

     

    Additional information

    Application

    Brush
    Colour

    White
    Placement

    Internal
  • Uses

    Airtight White – Spray or Roll for a Seamless Finish

    Passive Purple Airtight White is a liquid-applied airtight vapour control membrane designed for projects where airtightness must be achieved without compromising appearance. Applied by airless spray or roller, it creates a smooth, white finish that can be left on show — making it ideal for retrofit projects, heritage buildings, and internal spaces where a clean look is required.

    Why Airtight White?

    • ✅ Retrofit Ready – Perfect for upgrading existing buildings without the need to strip back walls.

    • ✅ On-Show Finish – The white coating blends seamlessly into interiors, making it suitable where airtight layers remain visible.

    • ✅ Fast Coverage – Up to 300m² per day can be applied by one installer using spray, or easily rolled on smaller projects.

    • ✅ Certified Protection – BBA Certified, Passivhaus Certified, and tested as a radon barrier for complete performance peace of mind.

    • ✅ Healthy & Safe – M1 Class, VOC-free, water-based, with zero harmful chemicals.

    • ✅ Fire Resistance – Achieves Fire Class C, outperforming traditional membranes.

    Where It Works Best

    Airtight White is designed for:

    • Internal retrofit airtightness upgrades

    • Areas where white needs to be left exposed (lofts, basements, services zones, car parks, lift shafts, stair wells or plant rooms)

    • Floor, wall, and ceilings

    • Vertical and horizontal areas

    • Service penetrations when paired with Airtight White Brush for detailing

    👉 Whether sprayed for large-scale speed or rolled for smaller retrofit projects, Airtight White delivers a seamless, durable, and attractive airtight layer that protects energy performance while looking good enough to leave uncovered.

  • Data Sheets & Certificates
    Technical Data Sheet
    Install Guide
    Airtight White SD Card
    BBA Certificate - Spray
    Passive Purple Safety Data Sheet
    PASSIVE HOUSE INSTITUTE CERTIFICATE
    Fire Class C
  • Architects Specification
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  • Delivery

    All delivery charges are included in the price of the products and are dependent on the products selected for purchase. This charge is based on delivery to mainland UK, excluding the Scottish Highlands & the Islands where additional shipping charges will apply. For more information read our delivery policy in full.

    Intelligent Membranes do not offer a next day delivery service.

    Intelligent Membranes aim for deliveries to be with the customer within 2 working days. During the festive period deliveries could take longer.

    Orders placed before 12pm will be dispatched the same day, any orders placed after 12pm will be dispatched the following working day

  • Returns

    We, at Intelligent Membranes, would like you to be 100% satisfied with your purchase and our service. In the unfortunate event of any item being unsuitable or wrong, please read our returns policy in full.

Airtight White —  Product FAQs

What is Airtight White (finished airtight paint)?
Airtight White is a finished internal airtight paint — the visible final surface that delivers airtightness with a clean white look. It’s ideal for retrofit and any space where the airtight layer must also be the finished wall/ceiling.

Is Airtight White a top coat?
No. It’s not a decorative top coat. Airtight White is the final airtight finish. If you ever refresh the surface, use a compatible coating per the latest TDS.

Where should I use Airtight White (retrofit & refurb)?
Internal walls and ceilings where you need a visible airtight layer with a white finish — occupied rooms, refurb/retrofit projects, corridors, plant rooms, showrooms.

Is Airtight White breathable (vapour-open)?
Yes — the film is airtight at all times to stop uncontrolled air leakage, yet vapour-open when the structure needs to release moisture, helping reduce condensation risk (especially in retrofit).

Which substrates are suitable?
Brick, block, OSB, plasterboard, cement board, sheathing boards and common internal plasters/boards that are clean, dry, and sound. Remove dust/loose material and fill obvious defects before coating.

Do I need a primer?
Often, yes.

  • IM Primer — general porous/dusty substrates.

  • Lime Prime — lime-based surfaces.
    Primers improve adhesion and help achieve a consistent film build.

How do I treat joints, corners and penetrations (use Brush + IM Fleece Tape)?
Use the Brush paste at board joints, corners/returns, frame perimeters and around pipes/cables.

  • Band width: aim for 100 mm total (≈50 mm each side). On rough masonry/high-movement joints, use 150 mm.

  • Gap guidance:

    • ≤3 mm: Brush can bridge directly.

    • 3–10 mm: seal with a compatible airtight sealant, then Brush over.

    • >10 mm: reinforce with IM Fleece Tape, embed, and over-brush to maintain continuity.

How much product do I need (consumption & coverage)?
Total (two-coat build), including detailing:

  • OSB / plasterboard / cement board: 0.8–1.0 kg/m²

  • Brickwork / blockwork: 1.2–1.4 kg/m²
    Heavily textured/porous areas or dense detailing can push usage to the top of the range. Always trial a small area first.

What coverage per 11.4 kg tub (approx.)?

  • Boards @ 0.8–1.0 kg/m² → ~14.25–11.4 m²/tub

  • Brick/block @ 1.2–1.4 kg/m² → ~9.5–8.1 m²/tub
    Quick calc: tubs = CEILING( area_m² × rate_kg/m² ÷ 11.4 )

Brush, roller or spray — which is best?

  • Brush (paste): joints/edges/penetrations; precision and bridging.

  • Roller (liquid): small–medium rooms; low overspray; consistent film.

  • Airless spray (liquid): large/open areas; fastest and most even film (masking + experienced operator recommended).

How do I apply Airtight White (step-by-step)?

  1. Prep & prime (clean, dry, sound; prime if needed).

  2. Detail with Brush on joints/corners/frames/penetrations (100–150 mm band; IM Fleece Tape for >10 mm).

  3. Field coat 1 (roller/spray) across the area, covering Brush bands; hit target wet-film.

  4. Field coat 2 after touch-dry to reach the total 0.8–1.0 kg/m² (boards) or 1.2–1.4 kg/m² (brick/block).

  5. Inspect & test: repair pinholes/holidays; verify airtightness (e.g., blower door) and check dry-film thickness per TDS.

How long does it take to dry / recoat?
Depends on temperature/humidity and ventilation. Follow the current TDS for touch-dry and recoat windows; ensure adequate airflow.

Can I repaint Airtight White later?
If a refresh is required, use a compatible coating per the current TDS so you maintain airtightness and vapour management.

How do I verify performance on site?

  • Airtightness testing (e.g., blower door)

  • Continuity checks at corners, frames and penetrations

  • WFT/DFT measurements against the specification

Common mistakes to avoid

  • Skipping primer on dusty/porous substrates

  • Thin spots/pinholes from under-building film

  • Not reinforcing >10 mm gaps with IM Fleece Tape before brushing over

  • Applying outside the temperature/humidity limits

Documentation & support
Ask for TDS, SDS, installation guides, and certificates. Installation support is available if you want guaranteed results.

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